1. Field of the Invention
This invention relates to a semiconductor integrated circuit having a plurality of modules whose functions can be alternatively exchanged for each other and a fabrication method for a semiconductor integrated circuit, and more particularly to recovery of decrease of the yield arising from a fault of a module in a semiconductor integrated circuit and a fabrication method for the semiconductor integrated circuit.
2. Description of the Related Art
In a semiconductor integrated circuit in recent years, refinement in working dimension and increase in scale of a circuit configuration have proceeded remarkably, and decrease of the yield arising from a fault in fabrication is getting serious. Since there is a limit to recovery of such decrease of the yield as just described only by optimization of fabrication conditions, a relief method against a fault using a redundant circuit has been and is being used. According to this method, a redundant circuit is provided in advance at part of an entire circuit and a fault portion is replaced by the redundant circuit thereby to prevent an entire semiconductor chip from becoming defective.
For example, a logic circuit data production method for an FPGA (field programmable gate array) is disclosed in Japanese Patent No. 3491579 (hereinafter referred to as Patent Document 1). According to the logic circuit data production method, the necessity for fault avoidance is decided from fault information and logic information and, where fault avoidance is necessary, the logic information is modified so that a function of the fault portion is substituted by a free portion.
A semiconductor apparatus is disclosed in Japanese Patent No. 3192220 (hereinafter referred to as Patent Document 2). According to the semiconductor apparatus, data transfer between a plurality of modules is performed by addressing of the memory map type. An ID code is allocated to each of circuit modules, and, the ID code is operated to control a transfer destination of data thereby to replace a fault circuit module by a redundant circuit module.
On the other hand, in recent years, the proportion of leakage power which occupies in entire power consumption of a semiconductor integrated circuit has been and is increasing radically, and a leakage power reduction technique using a power gate or a like element has been developed and has begun to be utilized. The power gate is a transistor for changing over the power supply between on and off and controls the power supply to any non-used module to an off state during operation of a system to decrease uselessness leakage power which is consumed otherwise where the power to the non-used module is controlled to an on state.
Further, since a dispersion of a fabrication process has become to have a significant influence on power consumption, also adjustment of the power supply voltage is performed for each of IC chips. For example, the power supply voltage to an IC chip which operates at a high speed is decreased while the power supply voltage to an IC chip which operates at a low speed is increased to establish the balance between the working speed of the IC chip and the power consumption and achieve reduction of power consumption. Also it is examined to dynamically change the power supply voltage in response to an operation state of the IC chip.